The popularity of the heavily marketed compact fluorescent light bulbs appears to have dropped dramatically this year on O'ahu — at least by one measure — even as energy customers face higher monthly bills.

Last year, O'ahu retailers sold about 700,000 CFL bulbs using special Hawaiian Electric Co. discount coupons. But as of Friday, the number of CFL bulb sales using the coupons has fallen to about 265,000.

HECO spokesman Darren Pai could not immediately explain the drastic drop in sales between 2007 and 2008.

"I can't speculate as to the overall trend in consumer behavior," Pai said. "We know that there were 700,000 sold in 2007. So it's possible that people have bought the CFLs that they need for now."

Nationwide, sales of CFLs nearly doubled between 2006 to 2007 — to 290 million, according to estimates by the Environmental Protection Agency. CFLs now make up about 20 percent of the U.S. light bulb market, according to the EPA.

Representatives for Longs Drug Stores, Foodland and Times Super Market — which all participate in HECO's CFL coupon program — did not return calls seeking comment on the program last week.

One retailer who uses the HECO coupons, however, said its sales of CFLs have increased.

Carol Ai May, vice president of City Mill Home Improvement Stores, would not provide specific sales figures but said, "our sales are actually going up."

City Mill is slowly reducing its inventory of traditional incandescent bulbs while increasing its stock and variety of CFLs, Ai May said.

"It's still not 50-50, but within a few years we will be 50-50," she said. "Eventually, with more people using CFLs, our sales will actually go down over time because CFLs last seven to 10 times longer."

Even with sales down this year, 1.25 million CFLs have been purchased using the HECO coupons since 2005.

HECO first tested the campaign in the last three months of 2005 as a way for customers to reduce energy use and saw 100,000 bulbs sell.

The following year, the number of sales jumped to 140,000 for the same three months of 2006 — then shot up to 700,000 for all of last year.

DOUBLE THE BENEFITS

The coupons save customers anywhere from $1 to $5 for certain CFL bulbs. They're designed to encourage HECO customers to buy the more expensive CFLs, which can result in energy savings of up to $24 per year per bulb.

"We're obviously seeing that people are making the switch to compact fluorescent lights," Pai said. "They help you save energy in two ways: They're much more efficient than an old-fashioned incandescent bulb, and they're not going to heat up a room like an old-fashioned bulb would. So you don't need to turn up the air conditioning or the fan when the lights go on."

A General Electric engineer named Ed Hammer is credited with inventing the compact fluorescent light bulb in 1976 at GE's labs in Nela Park, Ohio, during the first U.S. energy crisis. His prototype resides in the Smithsonian Institution.

One theory for the apparent drop in CFL sales on O'ahu through the HECO coupons could be their higher cost at a time when O'ahu residents are struggling to cut costs to make room for high gas, food and energy costs.

While a pack of four traditional 60-watt bulbs sold for $1.57 last week at the City Mill Home Improvement Center on Nimitz Highway, a single 13-watt CFL went for $3.98 — or $2.98 with a HECO $1 discount coupon.

"They are more expensive," said City Mill sales associate Terri Ford. "But I tell customers that they're going to last much longer, they're cooler and you'll save money down the line in electricity savings."

SAW IT FOR HERSELF

Electrician Judy Tokuda of Manoa looked over a City Mill display that compares actual energy use of a typical 60 watt bulb to a 15-watt CFL.

Tokuda has been replacing the old standard bulbs in her own home with CFLs and recommends that her customers switch, as well.

But Tokuda was still surprised at how fast the energy meter moved when she switched on the 60-watt bulb in the City Mill display, compared to the CFL, which barely moved the dial.

"Wow," she said, "it really does save a lot of energy."